Technique for reducing physical layer (PHY) overhead in wireless LAN systems

ABSTRACT

A physical layer (PHY) packet aggregation technique may be used to reduce the percentage of PHY overhead in data transmission in order to achieve better PHY efficiency and higher throughput. Higher layer packets in an upper layer data queue may be fragmented into appropriate small-size sub-packets, which include a body encapsulated by a MAC header and an FCS field. The sub-packets are then concatenated to form the data field of an aggregated PHY packet. Since each of the sub-packets contains its own MAC (Media Access Control) header and FCS (Frame Check Sequence) field, the receiver can identify and flag erroneous sub-packets on an individual basis. The receiver may transmit a block ACK, which includes the acknowledgement status for each of the sub-packets in the aggregated PHY packet, to the transmitter. The transmitter may resend only the erroneous sub-packet(s).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser. No. 60/523,439, filed on Nov. 19, 2003.

BACKGROUND

The IEEE (Institute of Electrical and Electronics Engineers) 802.11 family of standards (including IEEE 802.11, 802.11a, 802.11b, 802.11g, and 802.11n) specify over-the-air interfaces in a wireless LAN (Local Area Network), e.g., between a wireless client and a base station or another wireless client. The IEEE 802.11 standards place specifications on the parameters of both the physical (PHY) and medium access control (MAC) layers of the network. The PHY layer, which handles the actual transmission of data between nodes, may use direct sequence spread spectrum (DSSS), frequency hopping spread spectrum (FHSS), or infrared (IR) pulse position modulation. The MAC layer uses a set of protocols to manage and maintain communication between 802.11 clients/stations by coordinating access to the shared wireless medium. The MAC layer is responsible for performing a number of functions including scanning, authentication, and association.

The IEEE 802.11g standard specifies fixed PHY (Physical Layer) overheads for each data packet regardless of packet size or data rate. Therefore, the percentage of PHY overhead with respect to packet duration is larger for packets with fewer data bits or a higher PHY data rate. Furthermore, the percentage of PHY overhead (with respect to the transmission time for a data packet) may increase for the next generation wireless LANs. For example, the proposed IEEE 802.11n specification (directed to high throughput wireless LANs) seeks to improve the PHY data rate by a factor of three or four, but the preamble and signal fields in the header will still be transmitted at low data rates for high reliability. As a result, the transmission time for each data packet will become small, increasing the percentage of PHY overhead.

SUMMARY

A physical layer (PHY) packet aggregation technique may be used to reduce the percentage of PHY overhead in data transmission in order to achieve better PHY efficiency and higher throughput. Higher layer packets in an upper layer data queue may be fragmented into data units, e.g., an MPDU (MAC Protocol Data Unit). Each of the data units may be encapsulated by a MAC header and FCS (Frame Check Sequence) field to form a corresponding number of sub-packets. Each sub-packet may also include a scrambler field and a tail field.

The sub-packets are then concatenated to form the data field of an aggregated PHY packet. An indicator identifying the number of the sub-packets in the aggregated PHY packet may be included in the header of the aggregated PHY packet or an indicator may be added to at least a last sub-packet in the aggregated PHY packet to identify the last sub-packet to the receiver.

Since each of the sub-packets contains its own MAC (Media Access Control) header and FCS (Frame Check Sequence) field, the receiver can identify and flag erroneous sub-packets on an individual basis. The receiver may transmit an individual acknowledgement (ACK) for each sub-packet or a block ACK, which includes the acknowledgement status for each of the sub-packets in the aggregated PHY packet, to the transmitter. The transmitter may resend only the erroneous sub-packet(s).

The PHY packet aggregation technique may be utilized in a wireless LAN system, e.g., a system complying with one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16), and 802.20 families of standards. The technique may be implemented in a MIMO (Multiple-In Multiple-Out) systems, MISO (Multiple-In Single-Out) systems, SIMO (Single-In Multiple-Out) systems, and SISO (Single-In Single-Out) systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless multiple-in-multiple-out (MIMO) communication system.

FIG. 2 illustrates a PHY packet format conforming to the IEEE 802.11g specification.

FIG. 3A is a flowchart describing operations performed by a transmitter in a PHY packet aggregation technique according to an embodiment.

FIG. 3B is a flowchart describing operations performed by a transmitter in a PHY packet aggregation technique according to an alternative embodiment.

FIG. 3C is a flowchart describing operations performed by a receiver in a PHY packet aggregation technique according to an embodiment.

FIG. 3D is a flowchart describing operations performed by a transmitter in PHY packet aggregation according to an embodiment.

FIG. 4 illustrates sub-fragmentation of higher level packets into smaller sized sub-packets for aggregation into an aggregated PHY packet according to an embodiment.

FIG. 5 illustrates an aggregated PHY packet format according to an embodiment.

FIG. 6 is a plot showing simulation results.

FIG. 7 is a block diagram of a portion of the transmit section according to an embodiment.

FIG. 8 is a block diagram of a portion of the receive section according to an embodiment.

DETAILED DESCRIPTION

FIG. 1 illustrates a wireless multiple-in-multiple-out (MIMO) communication system 100, which includes a first transceiver 102 with M_(T) transmit (T_(x)) antennas 104 and a second transceiver 106 with M_(R) receive (Rx) antennas 108, forming an M_(R)xM_(T) MIMO system. For the description below, the first transceiver 102 is designated as a “transmitter” because the transceiver 102 predominantly transmits signals to the transceiver 106, which predominantly receives signals and is designated as a “receiver”. Despite the designations, both “transmitter” 102 and “receiver” 106 may include a transmit section 110 and a receive section 112 and may transmit and receive data. The antennas in the transmitter 102 and receiver 106 communicate over channels in a wireless medium. In FIG. 1, H 120 represents the reflections and multi-paths in the wireless medium

The wireless system may operate in compliance with one of the IEEE 802.11 family of standards (including IEEE 802.11, 802.11a, 802.11b, 802.11g, and 802.11n). The IEEE 802.11 family of standards specify over-the-air interfaces in a wireless LAN (Local Area Network), e.g., between a wireless client and a base station or another wireless client. The IEEE 802.11 standards place specifications on the parameters of both the physical (PHY) and medium access control (MAC) layers of the network. The PHY layer, which handles the actual transmission of data between nodes, may use direct sequence spread spectrum (DSSS), frequency hopping spread spectrum (FHSS), or infrared (IR) pulse position modulation. The MAC layer uses a set of protocols to manage and maintain communication between 802.11 stations by coordinating access to the shared wireless medium. The MAC layer is responsible for determining a number of functions including scanning, authentication, and association.

FIG. 2 illustrates the PHY packet format specified by the IEEE 802.11g standard. The PHY packet 200 includes a PHY header 202, which includes a preamble 204, signal field 206, and service/scrambler field 208, an MPDU (MAC Protocol Data Unit) 210, a tail field 212, and a PAD field 214. The preamble 204 is used to acquire the incoming OFDM (Orthogonal Frequency Division Multiplexing) signal, and train and synchronize the demodulator. The signal field 206 contains information about the rate and length of the PHY packet. The service/scrambler field 208 is used to synchronize the descrambler in the receiver. The tail field 212 is used for receiver processing functions. The PAD field 214 contains a number of bits used to modify the frame size to equal a specific multiple of bits coded in an OFDM symbol.

The MPDU 210 is the unit of data exchanged between two peer MAC entities using the services of the PHY layer. The MPDU 210 includes a MAC header 220, a body 222, and a FCS (Frame Check Sequence) field 224, which is used for error detection.

The IEEE 802.11g standard specifies fixed PHY overheads for each data packet regardless of packet size or data rate. Therefore, the percentage of PHY overhead with respect to packet duration is larger for packets with fewer data bits or a higher PHY data rate.

In an embodiment, a PHY packet aggregation technique is used to reduce the percentage of PHY overhead in data transmission in order to achieve better PHY efficiency and higher throughput. FIGS. 3A-3D are flowcharts describing a PHY packet aggregation and acknowledgement technique according to an embodiment. FIGS. 3A, 3B, and 3D show operations performed by the transmit section 110 of the transmitter 102, and FIG. 3C shows operations performed by the receive section 112 of the receiver 104. FIG. 7 is a block diagram showing a portion of the transmit section 110 in greater detail The transmit section may include a packet fragmenter 702 to fragment higher layer packets in an upper layer data queue 400 into appropriate small-size data units 404, as shown in FIG. 4 (block 300). An encapsulation module 704 may encapsulate each data unit 404 by appending a MAC header 406 and an FCS field 408 to form a sub-packet (S) (block 302). Other fields, such as, a service/scrambler field 410 and a tail field 412, may be appended to each sub-packet.

The sub-packets 402, with any appended field, are then concatenated by a PHY packet generator 706 to form the data field of an aggregated PHY packet 500 (block 304), as shown in FIG. 5. The aggregated PHY packet 500 may include a header 502, which may include a preamble 504 and a signal field 506, and a PAD field 508. The aggregated PHY packet may omit the service/scrambler 208 and tail 212 fields of a standard PHY packet if these are included in the individual sub-packets. For IEEE 802.11n systems, the PHY header 502 may also include an 802.11n PHY signal field 510 and an 802.11n preamble 512.

The length of the aggregated PHY packet may be selected based on several parameters. These parameters may include channel coherence time, channel availability (TXOP (Transmission Opportunity)), and quality of service (QoS) requirements such as delay and latency constraints. In an embodiment, the aggregated PHY packet may be less than 1/X of the channel coherence (which is inversely proportional to the Doppler spread of the channel), where X is a programmable number. For example, for X=20, a 10 Hz Doppler dictates that the packet length should be less than 1/20×0.1 sec=5 msec. The length of the aggregated PHY packet may dictate the number (M) of sub-packets 402 in the aggregated PHY packet.

The number (M) of sub-packets in the aggregated PHY packet may be identified in the PHY Signal field 506 (block 306). This information may be used to indicate to the MAC receiver the number of sub-packets that need to be processed, since at the MAC layer the sub-packets may be treated as individual packets. The aggregated PHY packet may then be transmitted to the receiver 104 (block 308).

In an embodiment, the number (M) of sub-packets in the aggregated PHY packet may not be known ahead of time, and due to hardware, firmware, and/or software buffer size constraints one may choose to aggregate sub-packets on the fly while the aggregated packet is being transmitted. In this case, the number (M) can not be specified at the PHY Signal field. As shown in FIG. 3B, which describes such an alternative embodiment, the transmit section begins transmission of the aggregated PHY packet before all sub-packets have been concatenated (block 305). The sub-packets may be aggregated on the fly, during transmission of the aggregated PHY packet (block 307). The transmit section 110 may signal each sub-packet, or at least the last sub-packet (block 309). Each sub-packet may be signaled by inserting, e.g., three unscrambled repeating bits before each sub-packet to indicate whether this is the last sub-packet in the aggregated packet. The receiver may use a majority rule method to decode the 3-bit repetition code to decide whether to continue receiving or stop, having reached the last sub-packet of the aggregated packet. Alternatively, a terminating sequence may inserted after the last sub-packet. The receiver would then process the packet until detection of the terminating sequence.

The receiver 104 receives the aggregated PHY packet (block 310, FIG. 3B). FIG. 8 is a block diagram showing a portion of the receive section 112 in greater detail. The receiver section 112 may include a sub-packet detector 802 to determine the number of sub-packets and/or last sub-packet in the aggregated PHY packet (block 311). The receiver may include a packet processor 804, which may process the sub-packets independently (block 312). Since each of the sub-packets 402 contains its own MAC header and FCS field, the receiver can identify and flag erroneous sub-packets on an individual basis (block 314). The packet processor 804 may include an error checking module 806 to perform this function. An acknowledgment (ACK) module 808 in the receiver 104 may then generate ACKs for the individual sub-packets and forward the ACKs for transmission to the transmitter 102. An additional MAC protocol may be defined to handle multiple ACKs from a single data packet.

In an embodiment, the receiver 104 may generate a “block ACK” that identifies any erroneous sub-packet(s) in the aggregated PHY packet (block 316). The IEEE 802.11e standard describes one type of block ACK. The transmitter may transmit a block ACK request frame after transmitting the aggregated PHY packet. The receiver then transmits the block ACK, which includes the acknowledgement status for each of the sub-packets in the aggregated PHY packet, to the transmitter 102 (block 318).

The transmitter 102 receives and inspects the block ACK (block 320, FIG. 3A) to determines whether the block ACK indicates any erroneous sub-packet(s) (block 322). If so, the transmitter may resend the erroneous sub-packet(s) individually (and expect individual ACKs) or in another aggregated PHY packet (block 324).

FIG. 6 shows the results of a simulation comparing the percentage of PHY overhead obtained with the packet aggregation scheme 602 and without the packet aggregation scheme 604 (as a function of packet size). The simulation was of a 3×3 MIMO 802.11n system using an EDCF (Enhanced Distributed Coordination Function) MAC protocol (802.11e MAC). The following assumptions were made: PHY data rate=54*3=162 Mbps; Doppler=10 Hz, leading to a channel coherence time of 100 msec and a maximum aggregated PHY packet spanning a maximum of 5 msec; sub-packet 402 body size (data unit 404)=MPDU body size; EDCF protocol is implemented with the block ACK feature enabled; and transmission assumes a queue with 64 MPDUs. As the plot shows, the packet aggregation scheme resulted in significant overhead improvement for the entire range of packet size.

The components of the transmit section 110 and receive section 112 shown in FIGS. 7 and 8, respectively, can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and/or combinations thereof.

The packet aggregation scheme may be implemented in MIMO, MISO (Multiple-In Single-Out), SIMO (Single-In Multiple-Out), and SISO (Single-In Single-Out) systems.

The packet aggregation and acknowledgement techniques described may be implemented in any packet-based wireless systems, e.g., systems compliant with IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, blocks in the flowcharts may be skipped or performed out of order and still produce desirable results. Accordingly, other embodiments are within the scope of the following claims. 

1. A method comprising: fragmenting data into a plurality of data units; appending at least an error checking field onto each data unit to form a plurality of sub-packets; aggregating the plurality of said sub-packets; generating an aggregated packet including the plurality of sub-packets and a single preamble; and transmitting the aggregated packet.
 2. The method of claim 1, wherein said aggregated packet comprises a physical layer (PHY) packet.
 3. The method of claim 1, wherein said aggregating comprises adding an indicator to the aggregated packet, said indicator indicating a number of sub-packets in the aggregated packet.
 4. The method of claim 1, further comprising: in response to receiving an indication that one or more of the sub-packets in the aggregated packet are erroneous, retransmitting said one or more of the sub-packets.
 5. The method of claim 4, wherein said receiving the indication comprises receiving acknowledgements for all but said one or more erroneous sub-packets in the aggregated packet.
 6. The method of claim 4, wherein said receiving the indication comprises receiving a block acknowledgement identifying said one or more of the sub-packets.
 7. The method of claim 1, wherein said aggregating further comprises appending at least one of a preamble field, a signal field, and a pad field to the aggregated packet.
 8. The method of claim 1, wherein said appending further comprises appending a header field to each of the data units to form the plurality of sub-packets.
 9. The method of claim 8, wherein said header field comprises a medium access control (MAC) layer header.
 10. The method of claim 1, wherein said appending further comprises appending a scrambler field to each of the data units to form the plurality of sub-packets.
 11. The method of claim 1, wherein said appending further comprises appending a tail field to each of the data units to form the plurality of sub-packets.
 12. The method of claim 1, further comprising: transmitting the aggregated packet over a wireless medium.
 13. The method of claim 12, wherein said transmitting comprises transmitting in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 14. The method of claim 12, wherein said transmitting comprises transmitting in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 15. The method of claim 1, wherein the plurality of data units comprise MPDUs (MAC Protocol Data Units).
 16. The method of claim 1, wherein said aggregating comprises adding an indicator to at least a last sub-packet in the aggregated packet to identify the last sub-packet.
 17. A method comprising: receiving an aggregated packet including a plurality of sub-packets and a single preamble, each sub-packet including a data unit and an error checking field; performing an error checking operation on each of the plurality of sub-packets in the aggregated packet; and in response to identifying one or more erroneous sub-packets, generating an indicator for each of the one or more erroneous sub-packets.
 18. The method of claim 17, further comprising: transmitting the indicator over a wireless medium.
 19. The method of claim 18, wherein said generating the indicator comprises generating acknowledgements for all but the one or more erroneous sub-packets.
 20. The method of claim 18, wherein said generating the indicator comprises generating a block acknowledgement identifying said one or more erroneous sub-packets.
 21. The method of claim 17, wherein said aggregated packet comprises a physical layer (PHY) packet.
 22. The method of claim 17, wherein said receiving comprises receiving in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 23. The method of claim 17, wherein said receiving comprises receiving in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 24. The method of claim 17, wherein each of said data units comprises a MPDU (MAC Protocol Data Unit).
 25. A transmitter comprising: a fragmenter to fragment data into a plurality of data units; an encapsulation module to append at least an error checking field onto each data unit to form a plurality of sub-packets; a packet generator to aggregate a plurality of said sub-packets into an aggregated packet and append a single preamble to the aggregated packet; and a transmit section to transmit the aggregated packet.
 26. The transmitter of claim 25, wherein said aggregated packet comprises a physical layer (PHY) packet.
 27. The transmitter of claim 25, wherein the packet generator is operative to add an indicator to the aggregated packet, said indicator indicating a number of sub-packets in the aggregated packet.
 28. The transmitter of claim 25, wherein the packet generator is operative to add an indicator to at least a last sub-packet in the aggregated packet to identify the last sub-packet.
 29. The transmitter of claim 25, further comprising: one or more antennas coupled to the transmit section, said one or more antennas operative to transmit the aggregated packet over a wireless medium; and in response to receiving an indication that one or more of the sub-packets in the aggregated packet are erroneous, retransmit said one or more of the sub-packets.
 30. The transmitter of claim 29, wherein said receiving the indication comprises receiving acknowledgements for all but said one or more erroneous sub-packets in the aggregated packet.
 31. The transmitter of claim 29, wherein said receiving the indication comprises receiving a block acknowledgement identifying said one or more of the sub-packets.
 32. The transmitter of claim 25, wherein the packet generator is operative to append at least one of a preamble field, a signal field, and a pad field to the aggregated packet.
 33. The transmitter of claim 25, wherein the encapsulation module is operative to append a header field to each of the data units to form the plurality of sub-packets.
 34. The transmitter of claim 33, wherein said header field comprises a medium access control (MAC) layer header.
 35. The transmitter of claim 25, wherein the encapsulation module is operative to append a scrambler field to each of the data units to form the plurality of sub-packets.
 36. The transmitter of claim 25, wherein the encapsulation module is operative to append a tail field to each of the data units to form the plurality of sub-packets.
 37. The transmitter of claim 36, wherein the transmitter is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 38. The transmitter of claim 36, wherein the transmitter is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 39. The transmitter of claim 25, wherein the plurality of data units comprise MPDUs (MAC Protocol Data Units).
 40. A receiver to receive an aggregated packet including a plurality of sub-packets and a single preamble, each sub-packet including a data unit and an error checking field, the receiver comprising: a receive section to receive the aggregated packet; an error checking module to perform an error checking operation on each of the plurality of sub-packets in the aggregated packet; and an acknowledgement module to generate an indicator for each of the one or more erroneous sub-packets in response to identifying one or more erroneous sub-packets.
 41. The receiver of claim 40, further comprising: one or more antennas to transmit the indicator over a wireless medium, said one or more antennas being operatively connected to the receive section.
 42. The receiver of claim 41, wherein the indicator comprises acknowledgements for all but the one or more erroneous sub-packets.
 43. The receiver of claim 41, wherein the indicator comprises a block acknowledgement identifying said one or more erroneous sub-packets.
 44. The receiver of claim 40, wherein said aggregated packet comprises a physical layer (PHY) packet.
 45. The receiver of claim 40, further comprising: a sub-packet detector to identify an indicator in the aggregated packet identifying a number of sub-packets in the aggregated packet.
 46. The receiver of claim 40, further comprising: a sub-packet detector to identify an indicator in the aggregated packet identifying a last sub-packet in the aggregated packet.
 47. The receiver of claim 40, wherein the receiver is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 48. The receiver of claim 40, wherein the receiver is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 49. The receiver of claim 40, wherein each of said data units comprises a MPDU (MAC Protocol Data Unit).
 50. A transmitter comprising: means for fragmenting data into a plurality of data units; means for appending at least an error checking field onto each data unit to form a plurality of sub-packets; means for aggregating a plurality of said sub-packets into an aggregated packet; means for appending a single preamble to the aggregated packet; and means for transmitting the aggregated packet over a wireless medium.
 51. The transmitter of claim 50, wherein said aggregated packet comprises a physical layer (PHY) packet.
 52. The transmitter of claim 50, further comprising: means for adding an indicator to the aggregated packet, said indicator indicating a number of sub-packets in the aggregated packet.
 53. The transmitter of claim 50, further comprising: means for adding an indicator to at least a last sub-packet in the aggregated packet to identify the last sub-packet.
 54. The transmitter of claim 50, further comprising: means for retransmitting said one or more of the sub-packets in response to receiving an indication that one or more of the sub-packets in the aggregated packet are erroneous.
 55. The transmitter of claim 54, wherein said receiving the indication comprises receiving acknowledgements for all but said one or more erroneous sub-packets in the aggregated packet.
 56. The transmitter of claim 54, wherein said receiving the indication comprises receiving a block acknowledgement identifying said one or more of the sub-packets.
 57. The transmitter of claim 50, further comprising: means for appending at least one of a preamble field, a signal field, and a pad field to the aggregated packet.
 58. The transmitter of claim 50, further comprising: means for appending a header field to each of the data units to form the plurality of sub-packets.
 59. The transmitter of claim 58, wherein said header field comprises a medium access control (MAC) layer header.
 60. The transmitter of claim 50, further comprising: means for appending a scrambler field to each of the data units to form the plurality of sub-packets.
 61. The transmitter of claim 50, further comprising: means for appending a tail field to each of the data units to form the plurality of sub-packets.
 62. The transmitter of claim 61, wherein the transmitter is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 63. The transmitter of claim 61, wherein the transmitter is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 64. The transmitter of claim 50, wherein the plurality of data units comprise MPDUs (MAC Protocol Data Units).
 65. A receiver comprising: means for receiving an aggregated packet including a plurality of sub-packets and a single preamble, each sub-packet including a data unit and an error checking field; means for performing an error checking operation on each of the plurality of sub-packets in the aggregated packet; and means for generating an indicator for each of the one or more erroneous sub-packets in response to identifying one or more erroneous sub-packets.
 66. The receiver of claim 65, further comprising: means for transmitting the indicator over a wireless medium.
 67. The receiver of claim 66, wherein the indicator comprises acknowledgements for all but the one or more erroneous sub-packets.
 68. The receiver of claim 66, wherein the indicator comprises a block acknowledgement identifying said one or more erroneous sub-packets.
 69. The receiver of claim 65, wherein said aggregated packet comprises a physical layer (PHY) packet.
 70. The receiver of claim 65, further comprising: means for identifying an indicator in the aggregated packet identifying a number of sub-packets in the aggregated packet.
 71. The receiver of claim 65, further comprising: means for identifying an indicator in the aggregated packet identifying a last sub-packet in the aggregated packet.
 72. The receiver of claim 65, wherein the receiver is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 73. The receiver of claim 65, wherein the receiver is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 74. The receiver of claim 65, wherein each of said data units comprises a MPDU (MAC Protocol Data Unit).
 75. A computer-readable medium having instructions stored thereon, which, when executed by a processor, causes the processor to perform operations comprising: fragmenting data into a plurality of data units; appending at least an error checking field onto each data unit to form a plurality of sub-packets; aggregating the plurality of said sub-packets; generating an aggregated packet including the plurality of sub-packets and a single preamble; and transmitting the aggregated packet.
 76. The computer-readable medium of claim 75, wherein said aggregated packet comprises a physical layer (PHY) packet.
 77. The computer-readable medium of claim 75, wherein said aggregating comprises adding an indicator to the aggregated packet, said indicator indicating a number of sub-packets in the aggregated packet.
 78. The computer-readable medium of claim 75, further comprising: in response to receiving an indication that one or more of the sub-packets in the aggregated packet are erroneous, retransmitting said one or more of the sub-packets.
 79. The computer-readable medium of claim 78, wherein said receiving the indication comprises receiving acknowledgements for all but said one or more erroneous sub-packets in the aggregated packet.
 80. The computer-readable medium of claim 78, wherein said receiving the indication comprises receiving a block acknowledgement identifying said one or more of the sub-packets.
 81. The computer-readable medium of claim 75, wherein said aggregating further comprises appending at least one of a preamble field, a signal field, and a pad field, to the aggregated packet.
 82. The computer-readable medium of claim 75, wherein said appending further comprises appending a header field to each of the data units to form the plurality of sub-packets.
 83. The computer-readable medium of claim 82, wherein said header field comprises a medium access control (MAC) layer header.
 84. The computer-readable medium of claim 75, wherein said appending further comprises appending a scrambler field to each of the data units to form the plurality of sub-packets.
 85. The computer-readable medium of claim 75, wherein said appending further comprises appending a tail field to each of the data units to form the plurality of sub-packets.
 86. The computer-readable medium of claim 75, further comprising: transmitting the aggregated packet over a wireless medium.
 87. The computer-readable medium of claim 86, wherein said transmitting comprises transmitting in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 88. The computer-readable medium of claim 86, wherein said transmitting comprises transmitting in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 89. The computer-readable medium of claim 75 wherein the plurality of data units comprise MPDUs (MAC Protocol Data Units).
 90. The computer-readable medium of claim 75, wherein said aggregating comprises adding an indicator to at least a last sub-packet in the aggregated packet to identify the last sub-packet.
 91. A computer-readable medium having instructions stored thereon, which, when executed by a processor, causes the processor to perform operations comprising: receiving an aggregated packet including a plurality of sub-packets and a single preamble, each sub-packet including a data unit and an error checking field; performing an error checking operation on each of the plurality of sub-packets in the aggregated packet; and in response to identifying one or more erroneous sub-packets, generating an indicator for each of the one or more erroneous sub-packets.
 92. The computer-readable medium of claim 91, further comprising: transmitting the indicator over a wireless medium.
 93. The computer-readable medium of claim 92, wherein said generating the indicator comprises generating acknowledgements for all but the one or more erroneous sub-packets.
 94. The computer-readable medium of claim 92, wherein said generating the indicator comprises generating a block acknowledgement identifying said one or more erroneous sub-packets.
 95. The computer-readable medium of claim 91, wherein said aggregated packet comprises a physical layer (PHY) packet.
 96. The computer-readable medium of claim 91, wherein said receiving comprises receiving in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 97. The computer-readable medium of claim 91, wherein said receiving comprises receiving in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 98. The computer-readable medium of claim 91, wherein each of said data units comprises a MPDU (MAC Protocol Data Unit).
 99. A system comprising: a transmitter comprising: a fragmenter to fragment data into a plurality of data units; an encapsulation module to append at least an error checking field onto each data unit to form a plurality of sub-packets; and a packet generator to aggregate a plurality of said sub-packets into an aggregated packet and append a single preamble to the aggregated packet; and one or more antennas coupled to the transmitter, said one or more antennas operative to transmit the aggregated packet over a wireless medium.
 100. The system of claim 99, wherein said aggregated packet comprises a physical layer (PHY) packet.
 101. The system of claim 99, wherein the packet generator is operative to add an indicator to the aggregated packet, said indicator indicating a number of sub-packets in the aggregated packet.
 102. The system of claim 99, wherein the packet generator is operative to add an indicator to at least a last sub-packet in the aggregated packet to identify the last sub-packet.
 103. The system of claim 99, wherein the one or more antennas are operative to retransmit said one or more of the sub-packets in response to receiving an indication that one or more of the sub-packets in the aggregated packet are erroneous.
 104. The system of claim 103, wherein said receiving the indication comprises receiving acknowledgements for all but said one or more erroneous sub-packets in the aggregated packet.
 105. The system of claim 103, wherein said receiving the indication comprises receiving a block acknowledgement identifying said one or more of the sub-packets.
 106. The system of claim 99, wherein the packet generator is operative to append at least one of a preamble field, a signal field, and a pad field to the aggregated packet.
 107. The system of claim 99, wherein the encapsulation module is operative to append a header field to each of the data units to form the plurality of sub-packets.
 108. The system of claim 107, wherein said header field comprises a medium access control (MAC) layer header.
 109. The system of claim 99, wherein the encapsulation module is operative to append a scrambler field to each of the data units to form the plurality of sub-packets.
 110. The system of claim 99, wherein the encapsulation module is operative to append a tail field to each of the data units to form the plurality of sub-packets.
 111. The system of claim 110, wherein the system is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 112. The system of claim 110, wherein the system is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 113. The system of claim 99, wherein the plurality of data units comprise MPDUs (MAC Protocol Data Units).
 114. A system comprising: a receiver to receive an aggregated packet including a plurality of sub-packets and a single preamble, each sub-packet including a data unit and an error checking field, the receiver comprising: an error checking module to perform an error checking operation on each of the plurality of sub-packets in the aggregated packet; and an acknowledgement module to generate an indicator for each of the one or more erroneous sub-packets in response to identifying one or more erroneous sub-packets; and one or more antennas to transmit the indicator over a wireless medium, said one or more antennas being operatively connected to the receiver.
 115. The system of claim 114, wherein the indicator comprises acknowledgements for all but the one or more erroneous sub-packets.
 116. The system of claim 114, wherein the indicator comprises a block acknowledgement identifying said one or more erroneous sub-packets.
 117. The system of claim 114, wherein said aggregated packet comprises a physical layer (PHY) packet.
 118. The system of claim 114, further comprising: a sub-packet detector to identify an indicator in the aggregated packet identifying a number of sub-packets in the aggregated packet.
 119. The system of claim 114, further comprising: a sub-packet detector to identify an indicator in the aggregated packet identifying a last sub-packet in the aggregated packet.
 120. The system of claim 114, wherein the system is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 121. The system of claim 114, wherein the system is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 122. The system of claim 114, wherein each of said data units comprises a MPDU (MAC Protocol Data Unit).
 123. A system comprising: a transmitter comprising: means for fragmenting data into a plurality of data units; means for appending at least an error checking field onto each data unit to form a plurality of sub-packets; means for aggregating a plurality of said sub-packets into an aggregated packet; and means for appending a single preamble to the aggregated packet; and one or more antennas coupled to the transmitter, said one or more antennas including means for transmitting the aggregated packet over a wireless medium.
 124. The system of claim 123, wherein said aggregated packet comprises a physical layer (PHY) packet.
 125. The system of claim 123, further comprising: means for adding an indicator to the aggregated packet, said indicator indicating a number of sub-packets in the aggregated packet.
 126. The system of claim 123, further comprising: means for adding an indicator to at least a last sub-packet in the aggregated packet to identify the last sub-packet.
 127. The system of claim 123, further comprising: means for transmitting the aggregated packet over a wireless medium; and means for retransmitting said one or more of the sub-packets in response to receiving an indication that one or more of the sub-packets in the aggregated packet are erroneous.
 128. The system of claim 127, wherein said receiving the indication comprises receiving acknowledgements for all but said one or more erroneous sub-packets in the aggregated packet.
 129. The system of claim 127, wherein said receiving the indication comprises receiving a block acknowledgement identifying said one or more of the sub-packets.
 130. The system of claim 123, further comprising: means for appending at least one of a preamble field, a signal field, and a pad field to the aggregated packet.
 131. The system of claim 123, further comprising: means for appending a header field to each of the data units to form the plurality of sub-packets.
 132. The system of claim 131, wherein said header field comprises a medium access control (MAC) layer header.
 133. The system of claim 123, further comprising: means for appending a scrambler field to each of the data units to form the plurality of sub-packets.
 134. The system of claim 123, further comprising: means for appending a tail field to each of the data units to form the plurality of sub-packets.
 135. The system of claim 134, wherein the system is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 136. The system of claim 134, wherein the system is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 137. The system of claim 123, wherein the plurality of data units comprise MPDUs (MAC Protocol Data Units).
 138. A system comprising: a receiver comprising: means for receiving an aggregated packet including a plurality of sub-packets and a single preamble, each sub-packet including a data unit and an error checking field; means for performing an error checking operation on each of the plurality of sub-packets in the aggregated packet; and means for generating an indicator for each of the one or more erroneous sub-packets in response to identifying one or more erroneous sub-packets; and one or more antennas operatively connected to the receiver, said one or more antennas including means for transmitting the indicator over a wireless medium.
 139. The system of claim 138, further comprising: means for transmitting the indicator over a wireless medium.
 140. The system of claim 139, wherein the indicator comprises acknowledgements for all but the one or more erroneous sub-packets.
 141. The system of claim 139, wherein the indicator comprises a block acknowledgement identifying said one or more erroneous sub-packets.
 142. The system of claim 138, wherein said aggregated packet comprises a physical layer (PHY) packet.
 143. The system of claim 138, further comprising: means for identifying an indicator in the aggregated packet identifying a number of sub-packets in the aggregated packet.
 144. The system of claim 138, further comprising: means for identifying an indicator in the aggregated packet identifying a last sub-packet in the aggregated packet.
 145. The system of claim 138, wherein the system is adapted to operate in accordance with at least one of the IEEE 802.11 (including 802.11, 802.11a, 802.11b, 802.11g, and 802.11n), IEEE 802.16 (including 802.16 and 802.16a), and 802.20 families of standards.
 146. The system of claim 138, wherein the system is adapted to operate in at least one of a MIMO (Multiple-In Multiple-Out) system, MISO (Multiple-In Single-Out) system, SIMO (Single-In Multiple-Out) system, and SISO (Single-In Single-Out) system.
 147. The system of claim 138, wherein each of said data units comprises a MPDU (MAC Protocol Data Unit). 